Aerosol dispensers have been available for a number of years for application of hair sprays and other personal care products, as well as for paints, lubricants, insecticides and a multitude of other liquid products.
In the earlier days of aerosol marketing, "Freon" blends were widely used as propellants, principally because they were not flammable and were relatively nontoxic. However, in recent years, it was discovered that "Freons," when released into the atmosphere, migrated to the upper stratosphere and contributed to the depletion of ozone. Since ozone shields the surface of the earth against penetration of solar ultraviolet radiation, the use of "Freon" propellants was believed by many to have contributed to climate changes as well as to an increased incidence of skin cancers and cataracts. Accordingly, the U.S. Environmental Protection Agency (E.P.A.) banned the further use of "Freon" propellants. This forced aerosol packagers to select from alterative propellant systems, all of which had serious disadvantages, among which were various hydrocarbons, consisting of blends of propane and butane mixtures. However, such hydrocarbon propellants are extremely flammable, and are in the chemical class known as volatile organic compounds, which are recognized as a significant cause of lower atmospheric air pollution or smog. Therefore, in even moderately populated areas of the country severe restrictions have been placed on the use of such compounds in many operations.
In addition to the selection of a gas propellant, a further problem in the aerosol packaging industry resides in the disposing of the used aerosol containers, particularly for large scale commercial users. After the product has been used up, the container remains charged with the propellant, and where the propellant is a flammable gas, the container is considered hazardous waste, even where the product is a water-based liquid.
In disposing of flammable propellants a particular problem arises with sparks upon puncture which might lead to explosion.
In addition to the concerns of discharging propellants into the atmosphere, which is coming under closer governmental regulation, there is the issue of costs, both in lost propellant and lost product. This invention addresses these issues with a unique solution.